Protesters rallying against the Eric Garner decision carried mock coffins bearing the names of victims of fatal police encounters as they crossed the Brooklyn Bridge on Thursday night.

UPDATED, 12:20 a.m. ET

Protesters fanned out across New York City on Thursday night, blocking traffic on major thoroughfares as they rallied for a second night against the recent killings of unarmed black men by white police officers.

As they clogged the Brooklyn Bridge, Manhattan Bridge, Holland Tunnel, West Side Highway and other roads and intersections, the demonstrators appeared to be even more organized than on Wednesday. The protests began that night when a grand jury decided not to bring charges in the Staten Island case of Eric Garner, who died after being put in a chokehold by a white police officer in July.

Protesters in Foley Square in Lower Manhattan on Thursday night.

IMAGE: JASON DECROW/ASSOCIATED PRESS

Protesters also gathered in other cities across the country Thursday night. They shut down Lake Shore Drive in Chicago, marched in Boston and chanted outside the police station in Ferguson, Missouri, where tensions are still running high after the killing of Michael Brown and another grand jury's decision not to indict the white police officer who shot him.

In New York, the demonstrations have caused massive traffic jams and prompted arrests. A mass of protesters also converged at the Staten Island Ferry terminal, which was being blocked by authorities. There were tense moments at the terminal as protesters and police scuffled near metal barriers while authorities attempted to block the entrance.

In Manhattan's Union Square, smaller groups of people, perhaps in clusters of a hundred each, joined together into what became a huge march up to Herald Square, Mash's Louise Roug reported.

Vincent Huff, a 34-year-old musician from Detroit also known as Trpl Blk, joined the protests at Union Square. "I felt like I had to come," he said. "This is a start ... you have so many people coming together from around the country."

Huff said police were being unfairly shielded from prosecution across America. "Numbers don't lie: You break down the numbers of black men being killed by police, the numbers don't lie," he said.

Anna Brennan, 32, joined the march to Herald Square on Thursday night after having watched the protests on Twitter and TV on Wednesday. Originally from Sydney, she moved to New York in 2011. "It's so intense — it's incredibly important to be here and to show solidarity," she said. "I've never been stopped or intimidated by the police, except when i've been with my peers, and most of them are black ... as a white person, it's a completely different ballgame. I live white privilege every day. I'm never afraid for my life. But I'm afraid for my friends' lives."

Thousands of protesters later converged on Times Square. Drivers, apparently not upset that they were in a standstill, honked in support. The demonstrations were met by police, some in riot gear, but the protesters seemed to have momentum and organization on their side. Some arrests were reported.

Earlier in the evening, the city's Office of Emergency Management warned residents of "extensive traffic delays" on the Brooklyn Bridge due to "protest activity," encouraging commuters to consider alternate routes.

When more than 5,000 began the night at Foley Square, near police headquarters, they remembered Garner, Brown and other unarmed black men killed by police with song before taking to the streets.

As the sounds of police sirens beeped intermittently and a helicopter buzzed above, protesters clapped their hands as they sang: "I still hear my brother crying, 'I can't breathe.' Now I'm in the struggle saying, 'I can't leave.' We're calling out the violence of racist police. We ain't gonna stop 'til our people are free."

Crowd organizers urged demonstrators in the green space near the New York Police Department's headquarters to be respectful of each other as a cordial tone blanketed the lively crowd.

Garner, a 43-year-old asthmatic, died in July. His final words were multiple pleas of "I can't breathe" as New York Police Officer Nick Palanteo had him in a chokehold. Brown died in August and the officer who shot him to death on a Ferguson street, Darren Wilson, was not indicted last week, prompting a string of violent and peaceful protests in many U.S. cities.

The mock coffins carried by protesters on the Brooklyn Bridge Thursday night.

IMAGE: JASON DECROW/ASSOCIATED PRESS

Wednesday night's demonstrations in New York, Oakland, San Francisco and Washington, D.C., caused disruptions and delays as protesters took over streets, highways and bridges, but they were largely peaceful.

At the Foley Square rally, where authorities estimated more than 5,000 had gathered, Constance Malcolm, the mother of Ramarley Graham, an unarmed black 19-year-old who was killed by plainclothes police in 2012 after being chased into his Bronx apartment, called on the crowd to remember Garner, to remember Brown, to remember her son, too.